It is generally known to establish equations of motion in order to determine a collision time for the current driving behavior of a vehicle and of a vehicle ahead. It is also generally known to determine target decelerations in order to avoid possible collisions.
EP 1 539 523 B1 and DE10258617B4 disclose a method and a device for triggering an automatic emergency braking process of a vehicle. The speed and the acceleration of the subject vehicle are determined and a minimum distance is set as a target safety distance. Furthermore, a target relative speed between the two vehicles is set that should be reached at the end of the automatic emergency braking process. In addition, the determined currently existing relative acceleration between the two vehicles is used.
DE 10 2006 019 848 B4 discloses a device for reducing the effects of a vehicle collision in which an obstruction is detected with its relative distance and its relative speed and a possible collision or accident is assessed, whereupon an occupant protection device may be activated. Such systems are also known as pre-crash systems.
JP 2004038245 A1 discloses an obstruction detector for vehicles with which a detected steering wheel operation is additionally used. EP 0 891 903 B1 discloses an automatic emergency brake function that assesses the possibility of avoiding an obstruction. EP 1 625 979 B1 discloses a method and a device for triggering emergency braking with which a probability of collision and furthermore a risk to the subject vehicle in the case of triggering of emergency braking are determined and the triggering threshold for the emergency braking can be varied depending on the determined risk. EP 1 803 109 B1 discloses a method for determining relevant objects close to a vehicle by which collision-relevant values are calculated from vehicle data and/or environmental sensor data including possible evasive maneuvers or braking processes.
Such conventional methods have the disadvantage that, in general, they are often restricted to only special driving situations and thus do not always contribute in a timely manner to avoiding accidents by autonomous braking. Furthermore, triggering of emergency braking may also take place too early and thus possibly unnecessarily.
Furthermore, various cruise control systems without emergency braking are known. For example, the Bendix-Wingman ACB adaptive cruise system with a braking property comprises a distance maintaining method for maintaining the distance to a vehicle ahead constant. Warning display signals and also emergency braking signals can be output for automatically carrying out an emergency braking process. For this purpose the distance to the vehicle ahead is measured, e.g., with radar.